I did the "fan test" & imo it isn't that effective at removing the dust considering how much was still in there when I eventually opened it up. I was wary of opening up my ps3 too, but it really isn't all that difficult & I'll be doing annual maintenance from now on. In hind sight, doing the "fan test" was an unnecessy risk & could have contributed to my ps3's early demise.
Oh, and btw, it looked more like pet dander rather than dust. You don't happen to have a have a dog, do you?